Hydraulic molding press



J. HALLER HYDRAULIC MOLDING PRESS June 2, 1953 Filed Aug. l2, 1950 l4 Sheds-Sheet 2 ,4a. tonlegs J. HALLER June -2, 1953 HYDRAULIC MOLDING PRESS Filed Aug. 12, 195o i a3 Z w gov Junez, 1953 J, HALLER 2,640,325

Y HYDRAULIC MoLnING PRESS- Filed 4Aug. 12.` 195o Gt megs June 2, 1953 J. HALLER HYDRAULIC MOLDING PRESS 4 Sheets-Sheet 4 Filed Aug. 12, 1950 ...mrz m :inventor Patented June 2, 1953 UNITED STATES PATENT oFFlcE HYDRAULIC MoLDING PRESS John Haller, Northvlle, Mich. Application August 12, 195o, serial No. 179,017

6 Claims.

lpowdered metal articles to precise dimensions.

Another object is to provide a hydraulic press of the foregoing character in which the motions of the plunger or plungers are limited by purely mechanical stop mechanisms or structures, thereby avoiding errors or accidents resulting from the misfunctioning or non-functioning of electrical or hydraulic stop devicescontrolled by limit switches.

Another object is to provide a hydraulic press of the foregoing character in which the stop mechanisms are controlled and adjusted by man- .ually operable stop operating means, such as screw and nut mechanisms.

Another object is to provide a hydraulic press of the foregoing character having oppositely movable plungers entering opposite ends of a mold cavity or bore, the distances to which both plungers will advance toward one another being pre- 4the upper portion of the press shown in Figure 1;

Figure 3 is a central vertical section through the lower portion of the press shown in Figure 1;

Figure 4 is a horizontal section taken along the line 4 4 of Figure 3;

`Figure 5 is a horizontal section taken along the line 5-5 in Figure 1; l

Figure 6 is a horizontal section taken along the line 6-6 in Figure 1; f

Figure 7 is a horizontal section taken along the line 'l-'l in Figure 2;

Figure 8 is an enlarged fragmentary side elevation of the micrometer stop mechanism for the lower outer plunger shown in the lower portion of Figure l;

Figure 9 is a diagrammatic central vertical secshowing the positions of the punches and mold or die at the conclusion of the mold filling operation;

Figure 10 is a view similar to Figure 9, but showing the mold cavity closed by the downward motion of the upper punch;

Figure 11 is a view similar to Figure 10 but showing the lower punch advancedto complete the molding operation;

Figure 12 is a viewsimilar to Figure l1 but showing the upper punch retracted to permit y ejection of the molded article; and

Figure 13 is a view similar to Figure 12, but showing the lower punch advanced still further upward to eject the molded workpiece.

General arrangement Hitherto, in the compression molding of articles from powdered material, such as powdered metal articles, it has been found difficult to precisely control the dimensions of the molded workpieces, and at the same time to provide an efficient and dependable press for this purpose. Attempts at controlling the halting of the molding punch or punches at precise locations by the use of electrical or electro-hydraulic devices controlled by limit switches have not been completely successful because of the lack of dependability of such devicesy and limit switches and the lack of preciseness in their operation. Similar shortcomings are possessed by control systems which mechanically shift the control valves of the hydraulic press in order to halt the punches or which employ sliding sleeves or other adjustable port arrangements for this purpose.

The present invention provides a molding press wherein the punches are caused to halt at precisely positioned locations by means of purely mechanical stop mechanisms and structures so that the punches will always approach one another to a predetermined separation and will then halt. This insures that the molded workpieces will always be of the same dimensions and will not vary in length. It also insures that compression will take place according to the desired compression ratio for the particular piece being molded. These stop mechanisms are operated manually and include screw-actuated devices which are capable of minute manipulation and unchanging adjustment when the stophas been positioned in its desired location. Locking arrangements, such as lock nuts, are provided to prevent accidental shifting of these stops during operation.

Referring to the drawings in detail, Figures l to located on opposite sides of the press i6 tween thestrain rods Se (Figures l and The luprights i8 are flanged or enlarged at their upper 8 inclusive show a hydraulic press generally designated i0, according to one form of the invention as consisting generallyT of a frame structure i2 carrying an upper plunger unit i3, a lower plunger unit ifi, and an intermediately-located press table unit l5. Associated with the units are a tubular mold or die i5 having upper and lower punches l1 and i8 respectively adapted to enter the opposite ends of vthe mold or die' bore or cavity i9. The punches il and it are tubular and a core rod Eil projects upward through the lower punch l and is held by a core rod bridge or support 2l. These elements will subsequently be described in more detail below.

The frame structure l2 consists of a press base 3l) and head 3l of approximately rectangular outline and drilled as at 32 and E3 respectively near their four corners to receive the lower and upper ends respectively of strain rods 3A. The ends of the strain rods 3d are threaded to receive internally-threaded nuts Sii by which the frame structure IE5 is held together. Tubular spacing members 31 are arranged between the press head 3l and the table unit i5, and the strain rods 36 are reduced in diameter immediately below the table I' dll of the table unit i5 so vas to provide annular shoulders iid upon which the table 38 rests (Figure l) The table 38 is bored as at lill for the passage of the reduced diameter upper portions of the strain rods 3d. The lower ends of the strain rods 3-1 are similarly reduced in diameter at the points where they enter the bores 32 above the base 35 so as to provide annular shoulders 4i at that location. In this manner a rigid frame is provided for supporting the various units of the press. Y

`In order to support the lower plunger unit M above the floor level, the bed S is supported upon verticalside plates 132 (Figure l)` which at their ylower ends are weldedor otherwise secured to an open-centered rectangular floor plate 43. The

Vside plates i2 are provided with cutaway portions 134% at their upper corners or provide clearance ings fili are also provided in two of the side plates o The press base il@ and side plates i2 together with the floor plate i3 form` a press base structure, generally designated 4E. The latter is enclosed by la closurel structure, generally designated lll, for the sake of appearance and exclusion of dirt. Theobridge structure 2i is bolted or otherwise suitably secured to a pair of up-rights and lowerends t9 and bolted to the press base :lil and table 3S respectively.

Upper plunger unit construction The upper plunger unit i3 (Figure 2) includes ,gaps 59 suitabler for the passage of fluid. This 'construction resembles that shown in Figure fl.

VThe lower end of the bore 56 is provided with a counterbore el) containing an annular packing si heid in piace by a 'ring or glane c2 bolted tu the lower portion 55 of the cylinder 50. The packing 'di engages a plunger generally designated 53 which at its upper end terminates in a piston head 64 having an annular shoulder 65 which is engageable at the lower end of its stroke with the radial stops 5B to limit the downward stroke of the plunger 63.

The upper end oi the plunger 83 is provided with acountersunk central surface 6B which is engaged by the lower end El of a screw stop 68 which is threaded into a. central threaded bore 69 in a cylinder head 'Hi which is bolted as at 'H to the upper end of the cylinder 5B (Figure 2) The cylinder head lil has an annular iiuid passageway for the nuts 36 (Figures l and 4). Access openl2 therein leading to a threaded port 13 for the admission and. discharge of fluid. Similarly, the flanged portion-5iof the cylinder 5l) also has a threaded port or passageway '14 leading to the portion of the cylinder bore 51 below the piston head Ed, and likewise adapt-ed to be connected to a' pressure huid supply or discharge pipe,

The threaded stop' $33 is provided with a cen'- tral cavity orj recess l5 closed at its upper end by a bushing 16' welded or otherwise suitably s'ecured thereto. rlhe bushing 'i6 is provided with a central hole 'il of square cross-section slidably receiving a 'square shaft 'rl having a portion 19 ci circular cross-section rotatably mounted in a bore 8d within an upstanding boss 8l rising from the cylinder head i6. A stud 82 threaded into a radial hole 83 in the circular cap S bolted tc the upper end ci' the boss Si engages a groove 85 in 'the shaft portion 8B so as to prevent the latter from moving upward or downward. It also serves as a locking screw to clamp the shaft 'l8` against rotation after it has been adjusted. The shaft portion 86 is rotatably mounted in a bore 8l in the cap dit and carries a hand wheel 88 secured as at 89 to the upper end of the' shaft portion 86. The bore lill is counterbored as at S8 to receive a packing Qi for preventing leakage around the shaft portion T9.

The lower end oi the plunger 63 is provided with a recess or cavity l5 closed at its lower end by a cap 9% bolted thereto and having a threaded `bore lll' therein threadedly receiving a screw shaft 98. 'i he screw shaft 98 is prevented from rotaclamping nut S9' which also threadedly receives the screw shaft Sel and which is integral with and extends downward from the cap 96. A split collar lil@ consisting ci halves HH and H12 which are pulled together by bolts |03 (Figure 7) serves to compress the split nut Q9 'and clamp the screw sha-ft 98 in its adjusted position.

The screw shaft S8 is provided with a polygonal portion ilhl'inimediately below its threaded portion for engagement by asuitable wrench in order to rotate the screw shaft 98 and make the necessary adjustment thereof. Below the polygonal portion ills' the screw shaft 93 is provided with a stepped portion lil below which is a circular head ille. The head m6 is seated in a cylindrical socket lill in a block 10S, the lower end of which is seated in a recess N39 in a cross head i it! (Figure 2) The Asocket HH is closed by a closure ring iii which is bolted tothe cross head lill byscrews l l2 which vpass through both the ring Hi and block i625. rI he cross head HB (Figure 6) has enlarged outer ends which are bored as at H3 to slightly engage vertical guide rods or posts i i4, the upper ends of which are seated in sockets H5 in the press head 3i. The' guide portions H6 bolted as at H1 tothelower surface of the press head 3|. The upper .tubular punch |1 is flanged (Figure 2) and held in position against the lower surface of the cross head ||0 by a retaining ring ||8 bolted thereto as at ||9 The punch |1 is provided with a central bore |20 of a diameter suitable for snugly but slidably receiving the upper end of the core rod 20. The outer diameter of the punch |1 is of a suitable diameter to snugly but slidably fit the mold bore |9, v

Lower plunger unit construction The lower plunger unit includes a lower cylinder |25 (Figure 3) having an outwardly extending ange portion |28 which is secured as by the bolts |21a to the .press base 30. The iiange |23 contains a threaded port or passageway |21 leading to an outer cylinder bore |28 closed at its outer or lower end by a cylinder head |29 bolted as at |300'r to the end of the cylinder |25. The cylinder head |29 also has a threaded port or passageway |30 which, along with the port or passageway |21, is connected to the service lines or pipes from a four-way Valve or a reversible hydraulic pump so that pressure fluid may alternately be supplied to one port while the other port is connected to a suction or discharge line, in accordance with conventional hydraulic [practice. The head |29 is bored centrally as at |3| (Figure 3) to receive a compound fluid conduit generally designated |32 which is enlarged as at |33 at its outer or lower end and secured as at |34 to the cylinder head |29. The compound conduit |32 consists of an inner long pipe |34 and an outer short pipe |35 coaxial with one another and providing inner and outer uid passageways |30 vand |31 respectively. The inner and outer .passageways |30 and |31 lead respectively to threaded external ports |38 and |39, respectively, both located in the enlarged portion |33 of the compound conduit |32.

Reciprocably mounted. in the outer cylinder bore |28 is a hollow outer lower plunger generally designated |40 having a piston head 4| and a reduced diameter hollow piston rod |42 leading through a reduced diameter bore |43 coaxial with the outer cylinder bore |28 to the open air. A packing |44 prevents leakage around the hollow piston rod |42. The .piston head |40 contains a stepped bore or opening |45 in which is secured, as by the bolts |46, an annular insert |41 having a central bore |48 snugly but slidably tting the outside of the outer conduit |35. Packings |49 prevent leakage along the bore |48. The stepped bore |45 opens into a bore |50 located within the piston rod |42, the outer conduit |35 terminating at its upper end inside the bore |50. In order to limit upward the stroke of the lower outer .plunger |40, the outer cylinder bore |28 above the piston head |4| is provided with projections or bosses |52 extending radially inward (Figure 4) and separated from one another by grooves |53. In this manner, the bosses or projections |52 serve as stops for limiting the upward stroke of the plunger |40 by engaging the annular shoulder |54 thereon when the piston head |4| has reached its maximum raised position.

Reciprocably mounted in the inner cylinder bore |50 within the hollow lower outer .plunger |40 is a hollow lower inner plunger, generally designated |55 having a piston head |58 and a hollow piston rod |51 with a cavity |58 inside it and ports |59 running from the cavity |58 to the bore |50 behind the piston head |58.` The piston 6.. head |53Y is, provided with a central bore |60 through which the inner conduit |34 passes and snugly engages,-a packing |8| preventing leakage therebetween. The annular shoulder |82 on the upper side of the piston head |56 serves as a'stop surface engageable with the annular surface |63 at the upper end of the inner cylinder bore |50. The upper end of the inner conduit |34 opens into the cavity |58 within the piston rod |51 of the lower inner plunger |55 so as to'supply or dis charge pressure fluid.

The upper end of the piston rod |51 is provided with an inwardly and downwardly extending threaded bore or socket |84 into which is threaded a screw shaft |85, the plain portion |68 of which passes through a bore |81 in a closure plate |68 and is enlarged at |89 at its upper end. Bolted or otherwise secured to the enlarged upper end |59 is a worm wheel |10 which is rotated by a worm |1| which is keyed or otherwise suitably secured to a shaft |12 (Figure 3) journaled at its opposite ends in the annular outer end |14 of a bracket |15, the hub |18 of which is bored as at |11 to slidably receive and engage one of the strain rods 34. The outer end of the shaft |12 is squared as at |18 (Figure 1) to receive a. hand crank (not shown) by which it may be rotated. The rotation of the shaft |12 and its worm consequently rotates the worm wheel |10 and screw shaft |85. Since the head |69 thereof is confined between the closure plate |08 and the base |19 of a lower .punch supporting structure, generally designated which is bolted to the upper side of the bracket outer end |14, th-e head |69 cannot move in either direction. Consequently, the lower punch support |80 rises and causes the closure plate |88 -to move upward away from the upper end |8| of an externally threaded sleeve |82. The sleeve |82 has a bore |83 therein snugly but rotatably tting the piston rod |51 and is rotated by a handle |84 in order to thread it into or out of a threaded bore |85 in the upper end |88 of the outer lower piston rod |42. A set screw |88a locks the sleeve |82 in its adjusted position. The piston rod |42 in turn is threaded externally as at |81 and is engaged by an internally threaded lock ring |88 rotated by a handle |89 secured thereto and also by an internally threaded ring nut or stop ring |90 rotated by a handle |9| secured thereto (Figure 3). The nut |90 is provided with a skirt or sleeve |92 (Figures 3 and 8) which has a beveled graduated lower edge portion |33 cooperating with a graduated vertical scale |94 to show the amount by which the nut |90 is rotated and consequently to show the amount by which the piston head |40 is lowered in the cylinder bore |28 at the lower end of its stroke. The stop ring |90 engages the upper end |95 of a stop sleeve |90, the lower end of which is flanged as at |91 and bolted to the upper end of the lower outer cylinder |25. The hollow piston rod |42 is keyed as at |91a to the stop sleeve |98, to permit sliding while preventing relative rotation.

The lower punch supporting structure |80 inV addition to the base |19 includes four uprights or posts |98 which at their upper ends carry a platform |99 having a central aperture 200 for the passage of the core rod 20 (Figure 1). The lower end of the core rod 20 is threaded into a lbore 20| in the bridge 2| so as to :be firmly and immovably anchored therein. The lower punch I8 is flanged and secured to the platform |99 by a ring 202 bolted or otherwise secured thereto.(Figure l). The mold or 1die |6 is inserted in a fbore 203 cfa stepped sleeve 264 (Figure i) which, in turn, is. inserted in a boreI 21051 in the mold or die table S3.

Adiust'mens before` operation Prior to operating the press tu, various adjustments are made. in order to adapt the press to the production oi' the particular workpiecey which to be made. The hand wheel 88 is rotated in one direction orv the other to. raise or lower the threaded stop 68' so aste limit the upward. motion of the upper plunger 53 (Figure 2:)2 The' screw shaft 981 is rotated by applying a wrench. to the hexagonal portion we alter loosening the 'bo-Its m3 in order to release the split clamping nut thereby enabling. the cross head: Im to be raised or lowered relatively to the plunger (i3- afnd. com sequenly to raise. or lower the upper tubular punch tl to the desired'. height,

The uppermost knob or handle its @Figure 3U" is. used to' rotate the threaded sleeve |-82 in order to. raise or lower its abutment end HM and thus limit the downward. stroke of theV inner plunger |55 relatively to the outer plunger Mic. The mid dlehandle |88' is used to rotate the: threadedlock ing ring |88 to enable the operator torotate the threaded stop ring Iilby means of the handley |:Q|., in order to limit the downward stroke ot the outer piston |413. Thus, the operator lowers the outer pistonl MB in. order4 to. obtaina longer stroke', since. the upward stroke-of the outer piston with is limited by `the shoulders or bosses |52, Similarly, the. upward stroke of. the inner piston. |35- is limited by the engagement of the upper side of the inner piston head lri with the shoulder at the upper' end oi the inner cylinder bcrelliiili. The extent to winch the stroke of thev outer plunger 1&9: is lengthened or shortened is indicated. by they micrometer scales |:93 and |91@ (Figure 81).

In order to. adjust. the height oithe lower outer tubular punch t8, the. operator applies a wrenchto the square; shaft H8' the outer end of the worm shaft |72, rotating the worm Hl- (-Figul'e'f) and consequently the worm wheel |91!) so aste ro tate the screw shaft hid upward'. or downward within the threaded boue |1841 at the. upper end. oli the plunger roelI |55! of the inner plunger |55. This action. raises, or lowers the; entireA lower punch supporting structure: Mit bodily relatively to the: lower inner plunger |55, together with the bracket |15; The core rod 2B is adjusted during the original assembly of the press` and is afterward held in fixed. position- In this mannen the making ot thev foregoing adjustments determines accurately the. distances to which'- the upper and lowerpunches, lil andi ll approach one another and consequentlydetermine the; exact size of. the molded workpiece. These adjustments; are unyielding. except at the will of the opera-tor, hence. worltpieces cannot vary in dimensions. as aVA result ot defects.. electrical contrclsystems or failure of controls, as' ink prior types of presses.. The adjustments. of the press of the present invention are purely mechanical and absolutely positive as is apparent from` the construction.

The. press` Hlis, of. course, connected. to a con"- ventional hydraulic, circuit. employing either a conventional reversible hydraulic pump o'a conventional four-way valve which. in turn,4 is connected, to ay hydraulic pump.. The word hydraulic" is. of. course,. intended to include any pressure liquid operatedlpump and'c'ircuit and' not merely, one operated by water; sinceof' course, oil is actually used as the'worllzingiliu in' manyhye 'draul'ic pump circuits'. When' so connected, the

ports |22'.- and |39 (Figure 3) become the service ports. of the lower outer plunger mi), the ports |39 and |331 become the service portsv for the lower inner plunger 5, and the ports 13e and 'hl (Figure 2) become the service ports for the upper hydraulic plunger 53. In operation, the supplying. oi pressure fluid to one port of each pair and the connection of the other port of the pair to the suction side of the pump causes the plunger to travel in one direction as well as the reversal of the supply of pressure duid causes the plunger to travel in the opposite direction.

In order to supply the die cavity |9 with powdered metal or other powdered material for the molding operation, a conventional feeding chute or shoe (not shown) is slidably mounted on the top of the table 39 so as to move back andforth beneath the upper punch |l and over' the mouth of the. die cavity or bore |9. Such feeding chutes are welll known in the powder metallurgy art and require no detailed description.

Operation With the various elements-of the press |18 lined 11p-andadjusted for the production of the particula-r workpiece, for example the bearing bushing W shown inA Figure 13, the operator retractsv the upper punch l'lto-'the` position shown in Figures 1 and 9- by supplying pressure huid' to the lower port 1s (Figure 2) or" the upper hydraulic cylinder Sii and discharging uid from the upper port l3= thereof. The lower punch is* is placed in the position shown in Figures 1 and 9, closing the lower end of the mold bore or die cavity HlV with the outer and inner plungers istV and 55 at their lowerm'ost positions, asr regulated' by the outer and' inner stop members |96 and |82 respectively (Figure 3').

The parts now occupy the position shownin Figures 1 and 9', the core rod" 2% of course bci-ng stationary with its' upper end rl'ush with the top of the die or mold it. The operator then operates the llling mechanism (not shown-l to ull the die cavity or mold bore I9 with powdered metal or other powdered; material, such asv powdered iron or bronze, the charge' P of powdered in'etal filling the mold cavity'. The operator now supplles'pressure fluid to the upper port i3- of the upper hydraulic cylinder 5G, and discharges fluid from the lower port 'i4' thereof, causing the upper plunger 63l to descend, thereby causing the upper punch l? to enter the mold cavityI tl? and close the upperl end thereof, the upper end of the core rodE 20 entering the central bore of the punch VF (Figure 1C). In this position, the llower annula-r shoulder E5 beneath the piston head- 5d' 0|. the upper plunger G3 engages theA radial bosses 58 Within the cylinder 50 (Figure 2)' and halts the plunger 63 and upper punch I1? in a prede-i termined position;

The operator now supplies pressure 'uidto the lower outer port |13@l of the lower hydraulic` cyln'der |25 and discharges fluid from the upper outerv port |217- thereof` (Figure 3), causing the lower outer plunger |40? torise until the annular surface |518 on itspiston head' Ml' engages the radialstop bosses |52 (Figures 3'v andi), halting the upward motion oi the lower outer plunger |463: Meanwhile, thishas c'ausedthe lower punch |8- tomove upward in the dies cavity l@ (Figure 11'); compressingV the powdered material;` P into the size desired for the final workpiece W.

The-operator now supplies pressurefluid tothe lower' port M in the upperhydraulic' cylinder 5U and discharges duid from` the' upper port 'i3'- so' as to cause the uppernplunger 63 and upper punch I1 to rise and be retracted, halting when the recessed top surface 66 -of the piston head 841 engages the lower end 61 of the threaded stop B8, whereupon the upper plunger 53 and the upper punch I? halt. The parts now occupy the positions shown in Figure 12.

To eject the finished workpiece W, the operator now supplies pressure fluid to the lowerport |38 and connectsthe lower. port |38 of the conduit structure |32 to discharge iiuid. Pressure fluid flows upward into the space beneath the lower inner plunger |55, causing the latter to rise until the annular shoulder |62 on ythe upper side of the piston head |56 engages the annular surface |63 at the upper end of the inner cylinder bore |50 (Figure 3). This action causes the lower punch supporting structure |353 andthe lower punch i8 to rise still further while the outer plunger |40 is. halted against its stops, cjecting the molded workpiece W from the die cavity |53 (Figure 13). The workpiece W may then be removed to a sintering oven and sintered in the usual manner. The outer and inner plungers |40 and |55 are then retracted by reversing the foregoing procedure and supplying pressure fluid to the ports |21 and |38 respectively (Figure 3), returning the outer and inner plungers |40 and |55 to their lowermost positions shown in Figures l and 8, with the plate |68 engaging the upper end |8| of the threaded sleeve |82 as a stop, The parts have now returned to the positions shown in Figure 9, and the die cavity I9 is refilled with powdered material and the foregoing operations repeated.

What I claim is:

l. A compound hydraulic motor comprising a cylinder having an outer cylinder bore therein, a tubular outer plunger reciprocably mounted in said outer cylinder bore and having a threaded portion disposed externally of said cylinder, a work element connected to said 'tubular plunger, a stop abutment member stationarily mounted adjacent said threaded plunger portion, a threaded stop member threaded upon said threaded plunger portion and abuttingly engageable with said abutment member at a predetermined location in the stroke of said tubular plunger, said tubular plunger having an inner cylinder bore therein, an inner plunger reciprocably mounted in said inner cylinder bore and extending through said tubular plunger and having a threaded portion disposed outwardly of said tubular plunger. said work element having a threaded portion threadedly and adjustably engaging said inner plunger portion, and a fluid conduit structure extending into said cylinder bore and through said tubular plunger into said inner cylinder bore, said inner plunger having a chamber therein communicating with said inner cylinder bore, and said conduit structure having a portion thereof extending through said inner plunger into said chamber.

2. A compound hydraulic motor comprising a cylinder having an outer cylinder bore therein, a tubular outer plunger reciprocably mounted in said outer cylinder bore and having a threaded portion disposed externally of said cylinder, a work element connected to said second plunger, a stop abutment member stationarily mounted adjacent said threaded plunger portion, a threaded stop member threaded upon said threaded plimger portion and abuttingly engageable with said abutment member at a predetermined location in the stroke of said tubular plunger, said tubular'plunger having an inner cylinder bore thereir'ran inner plunger reciprocablyv mounted in said inner cylinder bore and extending through said tubular plunger and having a threaded portion disposed outwardly of said tubular plunger, said work element having a threaded portion threadedly and adjustably engaging said inner plunger portion, and a uid conduit structure extending into said cylinder bore and through said tubular plunger into said inner cylinder bore, said inner plunger having a chamber therein communicating with said inner cylinder bore, said conduit structure having a fluid passageway therethrough opening into said cylinder bore and a portion thereof extending through said inner plunger into said chamber and having a separate fluid passageway through said extending portion and opening into said charn-` ber.

3. A compound hydraulic motor comprising a cylinder having a cylinder bore therein, a plunger reciprocably mounted in said cylinder bore and having a threaded portion disposed externally of said cylinder and coaxial with said cylinder bore, a stop abutment member stationarily mounted adjacent said threaded plunger portion, a threaded stop member threaded upon said threaded plunger portion and coaxial therewith, said threaded stop member being abuttingly engageable with said abutment member at a predetermined location in the stroke of said plunger, said plunger having a work element receiving portion, and a work element carried by said work element receiving portion and extending outwardly from said cylinder beyond said threaded plunger portion and stop member.

4. A compound hydraulic motor comprising a cylinder having an outer cylinder bore therein, an outer tubular plunger reciprocably mounted in said outer cylinder bore, a work element connected to said tubular plunger, said outer plunger having an inner cylinder bore, an inner plunger reciprocably mounted in said inner cylinder bore and extending through said tubular plunger and having a threaded portion disposed outwardly of said tubular plunger, said work element having a threaded portion threadedly and adjustably engaging said inner plunger portion, and a uid conduit structure extending into said cylinder bore and through said tubular plunger into said inner cylinder bore.

5. A compound hydraulic motor comprising a cylinder having an outer cylinder bore therein, an outer tubular plunger reciprocably mounted in said outer cylinder bore and having a threaded portion disposed externally of said cylinder and coaxial with said outer cylinder bore, a stop abutment member stationarily mounted adjacent said threaded plunger portion and a threaded stop member threaded upon said threaded plunger portion and coaxial therewith, said threaded stop member being abuttingly engageable with said abutment member at a predetermined location in the stroke of said tubular plunger, said outer plunger having an inner cylinder bore, an inner plunger reciprocably mounted in said inner cylinder bore and having a portion extending outwardly through said tubular outer plunger, a work element mounted upon said inner plunger externally of said sleeve, and a fluid conduit structure extending into said cylinder and through said tubular plunger into said inner cylinder bore.

6. A compound hydraulic motor comprising a cylinder having an outer cylinder bore therein, an outer tubular plunger reciprocably mounted 'in sam outer 'cylinder 'bore and having a threaded portion disposed externally 'of said cylinder and coaxial with 'said outer cylinder bore, a stop abut ment member stationar'ily mounted adjacent said threaded plunger portion and 'a threaded stop member threaded upon said threaded plunger portion and coaxial therewith, said threaded stop `member being abuttingly engageable with said abutment member at 'a predetermined location in the stroke of said tubular plunger, said outer plunger having an inner cylinder bore `and also an internally-threaded bore at the outer end thereof, an externally threaded stop sleeve threaded into said internally threaded bore, an

.inner plunger reciprocably mounted in said inner cylinder bore and having a portion extending outwardly through Vsaid tubular outer plunger and through said Stop sleeve, 'a Work 'element mounted upon said inner plunger externally of said sleeve and abuttingly engageable with said sleeve at a 'predetermined location in the Vstroke of said inner plunger, and a fluid conduit' structure exten-ding into said cylinder and through said tubular plunger into said inner cylinder bore.

JOHN HALLER.

References Cited in the le of this patent UNITED STATES PATENTS 

